Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual é a capacidade para b nacional - basquete?
 ###Tabelas: CREATE TABLE most-viewed_channels (most-viewed_channels_id AUTO_INCREMENT PRIMARY KEY, Position INT, Channel VARCHAR, Owner VARCHAR, Share (%) INT, Rating (%) INT) CREATE TABLE main_sports_clubs (main_sports_clubs_id AUTO_INCREMENT PRIMARY KEY, Club VARCHAR, Leagues VARCHAR, Venue VARCHAR, Location VARCHAR, Capacity INT, Established INT) CREATE TABLE 1992_winter_olympics (1992_winter_olympics_id AUTO_INCREMENT PRIMARY KEY, Date of Issue VARCHAR, Theme VARCHAR, Denomination VARCHAR, Printer VARCHAR, Quantity VARCHAR, Design VARCHAR, Perforation VARCHAR, First Day Cover Cancellation VARCHAR) CREATE TABLE practice_times__&__leaderboard_superstock_tt (practice_times__&__leaderboard_superstock_tt_id AUTO_INCREMENT PRIMARY KEY, Rank INT, Rider VARCHAR, Sat 29 May VARCHAR, Mon 31 May VARCHAR, Tues 1 June VARCHAR, Wed 2 June VARCHAR, Thurs 3 June VARCHAR, Fri 4 June VARCHAR) CREATE TABLE season_by_season (season_by_season_id AUTO_INCREMENT PRIMARY KEY, Year VARCHAR, Record VARCHAR, Finish VARCHAR, Manager VARCHAR, Playoffs VARCHAR)  
SELECT COUNT Capacity FROM main_sports_clubs WHERE Leagues = b national - basketball